I agree that a server should try to have administration at all times, but some times it's impossible.
Even having multiple admins to try and keep an eye on things isn't a guarantee.
I've seen dedicated servers where all the admins for the server live in the same time-zone, so when it's night-time for the host, all the admins go to sleep, and the server is left to fend for itself for 8~ hours.
And then I've seen (and hosted) servers where the host has to go away for a bit.
That can be something like half an hour, while they have their tea, or walk the dogs or whatever their daily lives ask for.
In those instances the host has gotten an administrator to look after the server while they're gone, rather than shutting down the server for the meantime and interrupting the fun of those still using the server.
But the problem then comes when the administrator has a chore to do, or something causes them to have to leave their post, which was unforseen.
They can't even close the server if they wanted to.
So, instead the server is left up unadministrated in the hopes that people will behave and have fun.
That doesn't always happen though. And that's because of people who will go out of their way to ruin a server when no admin is around.
I get that there are servers where there are never Admins, or Admins appear and do nothing for long periods.
But in general, it's quite tough being an Admin who has their own life to deal with alongside looking after a server.
And for some, it's just nicer to put some trust in the people on the server and try not to close the server, ruining everyones fun in the attempt to prevent someone else from ruining everyones fun.
What should be done in these situations, is that you should send a message to the Admins however you can.
RTB, Forum PM, leave it in the chat, write it in bricks, etc...
If the Admins return, then they should get your message and know what's happened.
If they haven't left the game, they should even be able to check their own chat and brown townyse what has happened.
Then they can punish those that need to be punished. Whether that's removing them from the server if they're still there, or banning them while they're not.
And I suppose if the Admins/Host do nothing, or don't even acknowledge it, then you know the server is probably not worth your time.